and automobiles. The name kirza is an acronym from Kirovskiy Zavod (Kirov plant) located in the city of Kirov, which was the first place of the mass production of kirza. The technology was invented in 1935 by Ivan Plotnikov and improved in 1941. Since that time kirza boots became a typical element of the uniform in the Soviet and Russian Army. 1935 Moscow Metro The Moscow Metro, which spans almost the entire Russian capital, is Europe's busiest metro system. Opened in 1935, it is well known for the ornate design of many of its stations, which contain numerous examples of socialist realist art. 1935 Kremlin stars 1936 Acoustic microscopy 1936 Airborne firefighting 1937 Artificial heart By Vladimir Demikhov. It was transplanted to a dog. 1937 Modern evolutionary synthesis By Russian-American geneticist and evolutionary biologist, Theodosius Dobzhansky 1937 Superfluidity By Pyotr Kapitsa, with John F. Allen and Don Misener 1937 Drag chute The drag chute or braking parachute is an application of the drogue parachute for decreasing the landing distance of an aircraft below that available solely from the aircraft's brakes. For the first time drag chutes were used in 1937 by the Soviet airplanes in the Arctic that provided support for the famous polar expeditions of the era. The drag chute allowed safe landings on small ice-floes. 1937 Drifting ice station Soviet and Russian drifting ice stations are important contributors to exploration of the Arctic. An idea to use the drift ice for the exploration of nature in the high latitudes of the Arctic Ocean belongs to Fridtjof Nansen, who fulfilled it on Fram between 1893 and 1896. However, the first stations to be placed right upon the drifting ice originated in the Soviet Union in 1937, when the first such station in the world, North Pole-1, started operating. More drifting ice stations were organised after World War II, and many special equipment was developed for them, such as the elevated tents to be placed on the melting ice and indicators monitoring the ice cracks. 1937 Welded sculpture Welded sculpture is an artform in which sculpture is made using welding techniques. The first such sculpture was the famous Worker and Kolkhoz Woman by Vera Mukhina. Initially it was placed atop the Soviet pavilion at the 1937 World's Fair in Paris. The choice of welding method was explained by a giant size of the sculpture, and also was intended to demonstrate